The present invention is an improvement over the Veress Needle which was originally designed for insertion into the chest to collapse a lung in treatment of tuberculosis. Later, when laparoscopy was first introduced to allow surgeons to look into the peritoneal cavity, the needle found new usage in filling the abdominal cavity with carbon dioxide. The Veress Needle comprises an outer cannula which has a needle point for easy penetration of the skin and underlying structures in the abdominal wall. The outer cannula expands into a relatively long needle hub which is used to house a spring mechanism for retraction of an inner cannula. This inner cannula includes a hollow tube having an enclosed end which is rounded to help avoid injury of the intra-abdominal structures. There is a side hole spaced above the distal end of the inner cannula to allow flow of carbon dioxide gas. Thus, when the needle point is pushed through the skin and other structures of the abdominal wall, the inner cannula will retract against the bias of the spring mechanism so that the blunt point of the inner cannula is fully retracted within the inner cannula to allow easy penetration all the way through the abdominal wall. After the abdominal wall is penetrated, the inner, rounded tip, snaps forwardly into the space of the abdominal cavity and pushes underlying movable structures out of the way, such as large or small bowels, omentum or liver. The gas is then delivered to the abdominal cavity via a gas delivery system which is connected to the upper hub or valve section of the Veress Needle by a long plastic delivery tube. This gas creates a space or work area within the abdomen whereby good visualization is provided through a separate laparoscope. Any definitive surgical procedures, such as tubal ligations must be done through a separate opening.
Although the Veress Needle has been a very useful instrument for about fifty years, it has certain drawbacks. It is a complex design and therefore expensive to manufacture. Because of its construction and small parts, the parts can be lost during cleaning and it is virtually impossible to clean the side hole adjacent the blunt tip of the inner cannula, resulting in small pieces of tissue and tissue fluid being transferred from one patient to the next. Also, after repeated use, the point becomes dull. Furthermore, the needle can be dislodged if left in place during an entire operative procedure and must be reinserted. Also, because of the rigid construction, the sharp end may be driven into the abdomen and cause damage to intra-abdominal contents such as the bowel, liver or major blood vessels if accidentally bumped by the surgeon. Furthermore, the Veress Needle can only be used for gas delivery and is not usable for a port hole for introduction of a laparoscope, operating instruments, cautery devices, laser fiber or other devices. If these devices are used they must be introduced through an additional trochar which creates an additional incision in the patient.
Other instruments have been devised which comprise concentric cannulas for various procedures. None of them provide the advantages of the present invention as will be discussed below. Among these instruments are the following:
Baren U.S. Pat. No. 2,630,803 Baren shows a pneumothoracic needle with spring-loaded inner blunt needle and an outer sharp cannula. The inner blunt needle is hollow and is removable without extracting the cannula from the chest wall.
McLaughlin U.S. Pat. No. 4,096,860 discloses an encatheter incorporating a plastic insertion conduit placed into a blood vessel with a needle. The structure includes an elastomeric sealing flapper or one-way valve that allows insertion of a syringe needle.
Spector et al. U.S. Pat. No. 4,424,833 describes a molded self-sealing gasket assembly through which, for instance, a catheter may be inserted and removed.
Yoon U.S. Pat. No. 4,535,773 shows a safety puncturing instrument and method using a shielding mechanism that is biased to protrude from the distal end of the instrument to shield its sharp, penetrating point after the point has penetrated.
Noiles U.S. Pat. No. 3,840,008 discloses a hypodermic needle for safely injecting fluid into nerve and vessel crowded areas of a patient. The needle has a pointed hollow piercing member slidably mounted about a fluid delivery tube. The delivery tube has a blunt nose with at least one fluid opening near its blunt end, the other end being connected to a conventional syringe. The hollow piercing member is connected to the delivery tube by a finger-operated collapsible bar. The bar is provided with a centrally located groove to facilitate collapse at the moment the operator removes the force of his finger. The blunt nose delivery tube is then free to penetrate the tissue of the patient without endangering nerve or vessel.